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  <title>Document</title>
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  <script>
    let str = ''
    let temp = null
    console.log(str == temp)
    // 空字符串与null用==判断不相等

    let str1 = '找不上商品布局单：商品编码：800008013900'
    console.log('indexOf: ', str1.indexOf('找不上商品布局单'))
  </script>

</body>

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